Air barrier testing is becoming a common – and sometimes mandatory – tool for measuring the performance of commercial, military and residential buildings, yet many people aren’t quite sure what an air barrier is, or how to prepare buildings for this rigorous test. In this post, we’ll focus on air barrier testing in military and commercial construction projects.
In simple terms, an air barrier is the boundary around a building that keeps outdoor air out and indoor air in. The idea behind having a continuous air barrier is to expend less energy and better control moisture and ventilation while improving comfort for the people in the building. Knowing the air leakage of a building ensures that general contractors will install the right sized HVAC equipment. If a building has oversized HVAC equipment, it can cause multiple issues related to indoor air quality, moisture management, and energy consumption. Air barrier design has traditionally been overlooked in commercial sized buildings; to create a high performance building, careful design and execution of an air barrier is key.
The Energy Policy Act of 2005 and other legislation has led to some major changes in the way buildings are built on military bases. The Army Corps of Engineers (USACE) has developed an air leakage protocol and target requirement to help the Army reduce energy consumption by controlling the unconditioned air entering the building. The targets also aim to reduce moisture issues. Air barrier tests in commercial buildings are relatively new and are something that many general contractors were slow to recognize when these specifications began to show up in projects. Projects that don’t plan ahead for these tests are often set up to fail from the start — and that can saddle commercial/military builders with costly retrofits at the end of construction just to meet the USACE specifications. I have heard stories of general contractors having to remove brick veneers to repair air barrier defects that could have been prevented by reviewing the design before construction started.
This infrared image shows serious breaches in an air barrier where the wall meets the ceiling.
There are a lot of people who are qualified to conduct an air barrier test on residential buildings; but this skill does not easily transfer to commercial buildings. Another challenge for the general contractor is finding a partner who can spot potential problems in a building before it becomes an expensive fix. Walls that penetrate the ceiling are often overlooked; in that situation drywall may give the appearance that it is sealed while in reality it can be a major air barrier break. The same goes for secondary air barriers around places like indoor mechanical rooms. Reviewing the plans prior to construction will identify potential problems ahead of time.
For commercial builders faced with meeting these new standards, design reviews early in the process and construction inspection throughout the construction process reflects forward thinking; and these steps will assure the air barrier is identified, in place, and functioning when it’s time for the witness test. This approach may seem more expensive at the start of a project but can usually end up saving the general contractors thousands of dollars because building science engineers can spot air barrier deficiencies and develop a solution before construction even starts.
Francis Conlin is a Senior Engineer at Southern Energy Management. Read more about him here.
Tags: air barrier, building science, energy efficiency, military
